For example, in high-speed vehicles such as Shinkansen, there is a need to ensure ride comfort without deteriorating the comfortability of the passengers even during high speed traveling.
For example, as shown in FIG. 9, when a high-speed vehicle, such as Shinkansen, travels in a tunnel section, a vortex is generated at a wall side of the tunnel. A yaw moment and a translational exciting force in a lateral direction, which are caused by pressure fluctuation due to the vortex, are imparted to a vehicle body, leading to an increase in the vibration of the vehicle body. This is already known, for example, in Non-patent Literature 1 below.
Furthermore, as also shown in FIG. 10, in general, when comparing the acceleration responses in the lateral direction of the vehicle body in a tunnel section and in a non-tunnel section, the response, particularly in the tunnel section, tends to rise in the vicinity of 2 Hz. Because the human sensitivity to such acceleration in the lateral direction is high especially in a low-frequency region, the acceleration in the lateral direction in the vicinity of 2 Hz generated in the tunnel section as described above has been a major problem for riding quality of the vehicle.
As a solution to such problem, in the Non-Patent Literature 1 below, there are already proposed and put in practical use a method in which an actuator is disposed laterally between a vehicle body and a bogie to damp vibration by generating a force in a direction opposite to the yaw moment exciting force caused by pressure fluctuation, and further, a method in which a so-called inter-vehicle longitudinal damper is provided between adjacent vehicles to damp vibration by dissipating energy caused by the yaw moment exciting force.
It should be noted that, in these methods already in practical use, the yaw moment, which is the source of the vehicle vibration while traveling in a tunnel, and the lateral translational exciting force itself are not reduced. Therefore, in the case where the source of the vehicle vibration is not cut off, the above-described exciting force becomes excessive. In this case, the problem is that the vehicle vibration reducing effect is small.
To address this problem, according to the above-described Non-Patent Document 1, a method is also proposed, in which a jet device is disposed on a side surface of the vehicle to reduce the yaw moment exciting force by directing a jet horizontally onto a wall of the tunnel during traveling in a tunnel.
Furthermore, in addition to the above, the following Patent Literatures 1 and 2 each disclose a construction for preventing a vortex generated under the floor of a vehicle from being swirled up around a side surface of the vehicle, which is different from the above-described construction in which a jet flow is used.